Experiment Results
Predict Question:
Predict Question: Predict what will happen to the resting membrane potential if the extracellular K+ concentration is
increased.
Your answer : b. The resting membrane potential will become less negative.
Stop & Think Questions:
What is the polarity of the resting membrane potential (voltage)?
You correctly answered: b. negative
What does it mean that the voltage just inside the membrane is negative?
You correctly answered: b. There are more negative charges than positive charges just inside the membrane.
The membrane of most cells, including neurons, contains passive, open,
K+ leak channels. Given the normal K+ concentrations and the resultant concentration gradient, which direction would K+
be expected to move (diffuse) through these leak channels?
You correctly answered: b. out of the cell
What effect does increasing extracellular K+ have on the net diffusion of K+ out of the cell?
You correctly answered: b. It decreases the net diffusion of K+
.
Which way would Na+ move across the membrane if there were open Na+ channels?
You correctly answered: a. Na+ would diffuse into the cell.
The membrane has open K+ channels, and changing extracellular K+ concentration results in a change in membrane
potential. Changing the extracellular Na+ concentration does not significantly change the membrane potential. What do
your results suggest about the number or state (open or closed) of Na+ channels in the resting membrane of a neuron?
You correctly answered: b. Na+ channels are mostly closed.
Quick Reply
